Motor controlled material spreading vehicles

ABSTRACT

A vehicle is provided with a material discharge apparatus operated by an auxiliary fluid driven motor and an adjustable control valve for the fluid motor. A control system for adjusting the valve includes an electric motor which is connected to an improved electric circuit for regulating the operation of the motor in accordance with vehicle speed and for automatically stopping the motor to shut off the discharge of material from the vehicle when the vehicle is stopped. The control circuit includes a potentiometer which is driven by the control motor to balance the control circuit. A gear cluster is arranged to drivingly connect the control motor with both the valve and the potentiometer. The gear cluster is connected to a manual control knob for manually shifting the gear cluster to a first override position to disengage the control motor from the valve, while maintaining the control knob in driving connection with the potentiometer and the valve. In this position the control knob is operable to manually adjust the valve independently of the control motor. The gear cluster may be manually shifted to a second override position to provide a coupling solely between the control knob and the valve to enable the valve and the control circuit to be synchronized. The valve includes a pair of slotted spools, one spool being rotatable to progressively bring the spool slots into passage-defining alignment. The slot of at least one of the spools has an enlargement at one end for enabling a greater-than-normal rate of fluid supply to the fluid motor when the valve is in an initially-open position.

United States Patent 8 [1 1 Sousek 1 MOTOR CONTROLLED MATERIAL SPREADING VEHICLES [75] Inventor: Eugene A. Sousek, Appleton, Wis. [73] Assignee: Koehring Company, Milwaukee,

Wis.

[22] Filed: Sept. 27, 1972 [21] Appl. No.: 292,821

[52] US. Cl 318/591, 318/610, 318/670,

318/618, 318/663, 318/672, 239/150, 239/670 [51] Int. Cl. G05b 7/00 [58] Field of Search 318/609, 610, 618, 625, 318/644, 674, 673, 672, 591, 663; 239/150, 675, 677, 670

[56] 8 References Cited UNITED STATES PATENTS 2,948,839 9/1960 Smith, Jr. et al. 318/610 X 3,395,866 8/1968 Sousek et al 239/670 Primary E.raminerT. E. Lynch [57] ABSTRACT A vehicle is provided with a material discharge apparatus operated by an auxiliary fluid driven motor and an adjustable control valve for the fluid motor. A con- [4 1, Mar. 4, 1975 trol system for adjusting the valve includes an electric motor which is connected to an improved electric circuit for regulating the operation of the motor in accordance with vehicle speed and for automatically stopping the motor to shut off the discharge of material from the vehicle when the vehicle is stopped. The control circuit includes a potentiometer which is driven by the control motor to balance the control circuit. A gear cluster is arranged to drivingly connect the control motor with both the valve and the potentiometer. The gear cluster is connected to a manual control knob for manually shifting the gear cluster to a first override position to disengage the control motor from the valve, while maintaining the control knob in driving connection with the potentiometer and the valve. In this position the control knob is operable to manually adjust the valve independently of the control motor. The gear cluster may be manually shifted to a sec- 0nd override position to provide a coupling solely between the control knob and the valve to enable the valve and the control circuit to be synchronized. The valve includes a pair of slotted spools, one spool being rotatable to progressively bring the spool slots into passage-defining alignment. The slot of at least one of the spools has an enlargement at one end for enabling a greater-than-normal rate of fluid supply to the fluid motor when the valve is in an initially-open position.

17 Claims, 12 Drawing Figures PATENTED N975 sum 2. 0F 4 PATENTEBHAR 41975 sum 3 o 9 Illlli MOTOR CONTROLLED MATERIAL SPREADING VEHICLES BACKGROUND OF THE INVENTION This invention relates to vehicles having auxiliary driven mechanisms. Of particular concern are auxiliary mechanisms for spreading material onto. roadways.

Vehicles have been heretofore proposed which are provided with auxiliary driven mechanisms, such as devices for dispensing and dispersing materials on the ground during vehicle travel. Such vehicles may commonly be utilized in urban areas, for example, for spreading sand, salt, chips or the like onto roadways. A device of this type is illustrated in Sousek, et al., US. Pat. No. 3,395,866, the disclosure of which is incorporated herein by reference.

In a vehicle of this nature it is conventional to employ a power-driven feed auger for dispensing material from a container on the vehicle and a power-driven spinner disc for dispersing or scattering this material. One or more auxiliary motors may be provided for driving these auxiliary driven devices.

To control the rate of deposit of material on the roadway, it is known to utilize a control system for automatically regulating the speed of an auxiliary motor which drives the feed auger. The control system may be in the form of an electrical circuit arranged to regulate the rate of operation of the auxiliary motor in relation to the speed of the vehicle. In this fashion, the amount of material spread during each unit of distance travelled by the vehicle will be constant in spite of variations in vehicle speed.

Although these known control systems are useful, they have not proved entirely satisfactory in some respects. The dependence of these systems upon vehicle speed is a desirable feature while the vehicle is moving along the roadway, but this becomes a complicating factor when the operator temporarily stops the vehicle. Also, the known systems were not capable of convenient operation with respect to the pounds-per-mile setting; it was not possible for example to establish a desired setting and then hold this setting of the control system in spite of temporary stops of the vehicle or periodic operator-initiated control override sequences for meeting particular material dispensing requirements.

Another type of difficulty has been encountered in connection with the known mechanisms in which the auxiliary motor is a hydraulic motor driven through a control valve from a pump connected to the vehicle englne. During relatively slow rates of travel of the vehicle, the valve will be oriented by the automatic control system to a slightly open or cracked position so that only a small passage is provided for admitting fluid to the motor. During this same time, the vehicle engine is' apt to be running slowly to operate the pump under minimal power. Consequently, the performance of the auxiliary driven fluid motor can be adversely affected in that a sufficient flow of driving fluid may not be supplied by the pump and valve arrangement.

SUMMARY OF THE INVENTION It is the general object of this invention toprovide an improved apparatus for dealing with problems of the types mentioned above.

A more particular object of this invention is to provide an arrangement for manually overriding an automatic control system normally operating an auxiliary driven mechanism on a vehicle.

Another object of this'invention is to provide such an arrangement which will automatically return the auxiliary driven mechanism to a pre-set mode of operation subsequent to manual operation.

Yet another object of this invention is to provide a fluid control valve which effects optimal performance of a vehicle-mounted, auxiliary driven mechanism during an initially-open position of the valve.

Still another object of this invention is to provide an improved electric control circuit for causing automatic operation of an auxiliary vehicle-mounted mechanism in accordance with vehicle speed while the .vehicle is moving and for causing the mechanism to stop when the vehicle stops.

These and other objects are accomplished according to a preferred embodiment of the invention wherein a vehicle is provided with at least one auxiliary driven.

mechanism, such as a material discharge apparatusf The material discharge apparatus includes a feed auger driven by a fluid motor and a valve for metering fluid under pressure to the fluid motor. In order to regulate the rate at which the valve supplies fluid to the motor, to thereby regulate the rate of material discharge, a control system is provided which includes a control motor having a driving connection with the valve. The

control motor is provided with a control circuit for operating the control motor in a manner which automatically drives the fluid motor at a predetermined rate in accordance with vehicle speed.

The control system is provided with a manually operable mechanism which is shiftable to an override position for disengaging the drive connection between the control motor and the valve. While in the override position, the manually operable mechanism remains operably coupled to the valve to facilitate manual operation thereof. In this fashion, the rate of operation of the auxiliary driven mechanism may be varied independently of the control motor and the control circuit.

In a preferred form of the invention, the drive connection between the control motor and the valve is in the form of a gear mounted on a rod, with one end of the rod being coupled to the valve. The manually operable-mechanism includes a manually shiftable control knob which is operable to longitudinally shift the rod to a first override position for disengaging the gear from the control motor. In such a first override position, the rod remains coupled to the valve through a slidable connection to afford manual adjustment of the valve by the manual control knob independently of the control circuit.

The control assembly further includes a follow-up system in the form of a potentiometer in the control circuit mechanically coupled to the control motor by a gear on the rod so as to be driven by the control motor during normal automatic operation of the discharge mechanism. This potentiometer serves to balance the control circuit when a desired orientation of the valve has been reached. According to the present invention, the manually operable control knob is operable when shifting the gear drive assembly to the first override position, to maintain a driving relationship between the control knob and the potentiometer. In this fashion, during manual operation of the valve in the first override position, the potentiometer will be driven by manual operation of the control knob to upset the balance in the control circuit so that when the control motor is recoupled with the valve, the imbalance in the control circuit will result in rotation of the control motor to automatically effect a return of the valve to its original, pre-set orientation.

The manually operable mechanism is further operable to shift the gear drive assembly to a second override position in which the drive connection between the control motor and the valve is disengaged, and further wherein the drive connection between the control knob and the potentiometer is also disengaged. In this position, the relationship between the'valve and the electrical control circuit may be adjusted by the control knob to effect a desired synchronization of the mechanism.

The valving assembly preferably comprises a spool arrangement having a stationary spool portion and a shiftable spool portion, each having an elongate aperture. The shiftable valve portion is in driving relationship with the gear assembly and is movable between a closed and an open position wherein the apertures become aligned to define a progressively larger fluidconducting passage. As the size of the passage becomes enlarged, increasing amounts of drive fluid will be metered to the fluid motor to effect an increase in the rate of material discharge. According to the present invention, the aperture of one of the valve portions is provided with an enlargement at one end which provides a greater-than-normal rate of fluid metering when the valve is disposed in a cracked, i.e., slightly opened, position. This assures that the auxiliary driven fluid motor will be provided with enough drive fluid to operate properly when the vehicle is traveling at relatively slow rates of speed.

The control .circuit for controlling the auxiliary motor preferably includes a generator for generating a first signal related to vehicle speed and a potentiometer driven by the control motor for generating a second signal relatedto the speed of the auxiliary motor. The control motor is driven in response to the relationship between the first andsecond signals through a switching circuit so that the speed ofthe auxiliary motor is related to the speed of the vehicle. Moreover, a manually adjustable energizing voltage is supplied to the potentiometer to provide for manual adjustment of the speed of the auxiliary motor for a given vehicle speed. Since the control circuit is arranged to automatically turn the auxiliary motor off and drive the potentiometer to a zero output voltage condition when the vehicle is at rest, adjustment of the energizing voltage does not affect auxiliary motor speed in the absence of the vehicle speed related first signal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a material-spreading vehicle embodying'the present invention.

FIG. 5B is an illustration of the valve in a closed position.

FIG. 5C is an illustration of the valve in an initially open position.

FIG. 5D is an illustration of the valve in a full-open position.

FIG. 6 is a front elevational view of a control box according to the invention.

. FIG. 7A is a schematic illustration of a manually shiftable gear assembly in a normal operating position.

FIG. 7B is a schematic illustration of the manually shiftable gear assembly in a first override position.

FIG. 7C is a schematic illustration of the manually shiftable gear assembly in a second override position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT According to a preferred embodiment of the invention, a vehicle 10 includes a prime mover 12 for propelling the vehicle and a cab 14 which provides an opera-' tors station having controls for both driving the vehicle any suitable manner such as disclosed in U.S. Pat. No.

FIG. 2 is a partial view, in perspective, of the rear portion of the spreader vehicle.

FIG. 3 is a schematic diagram of a hydraulically operated spreader mechanism and an electric circuit for controlling its operation.

FIG. 4 is a detail illustration, in section, of a gear assembly for operating an adjustable valve in accordance with the invention.

FIG. 5A is an exploded view, in perspective, of an adjustable fluid metering valve in accordance with the invention.

2,881,024 to Saiberlich. The body 18 comprises a spreader unit whichis operable to dispense sand, salt. chips, calcium chloride, or other materials onto a street or highway.

The spreader unit includes a container portion of generally truncated triangular configuration which deflnes a trough 20 at its bottom. A conveyor 22 of the rotary auger type is disposed in the trough and is operable, upon rotation, to advance material in the trough toward an opening 24 in the rear of the body 18. A vertical spreader housing 26 is disposed at the opening 24 and serves to guide the material downwardly toward a spreader skirt 15 which is attached to the lower end of the housing 26. Suspended within the spreaderhousing 26 is a rotatable spreader spinner assembly 28..The spinner assembly comprises a spinner disc 30, adrive shaft 32, and a fluid motor 34 which provides rotary drive for the spinner disc 30.

Disposed at an end of the auger conveyor 22 is a driven sprocket wheel 36 which is mechanically linked to a drive sprocket wheel 38 by.a suitable sprocket chain 40. The drive sprocket wheel 38 is mounted on a shaft 42 which is driven by a hydraulic motor 44 to rotate the auger conveyor.

In order to drive the auxiliary motors 34 and 44, a fluid circuit, preferably hydraulic, is provided and includes a pump 46 driven by a power take-off from the vehicle prime mover 12. The pump 46 is arranged to pump hydraulic fluid from a reservoir 50 through conduits 52 and 54 to a valve assembly 56. The valve. assembly 56, as will be described subsequently in greater detail, includes a pair of adjustable valves 58 and 60 which selectively direct fluid to the hydraulic fluid motors 44 and 34, respectively. Fluid to the conveyor motor 44 is fed through conduit 62 and returns to the reservoir via conduits 64, 66, and 68. A fluid return line The valves 58 and 60 each comprise a pair of spool portions 76 and 78 having elongated apertures or slots 80 and 82 (FIG. 5A). The spool portion 76 seats rotatably within a fitting 84 and includes a stem 86. The spool portion 78 remains stationary. Referring more particularly to FlGS. 3 and 4, rotation of the stem 86 of the metering valve 58 is effected by means of a drive arrangement which includes a control motor 88 having a gear 87, the gear being coupled to a gear 89 mounted on a rod 90. The rod 90is mounted within a sleeve 92 which is secured to the stem 86 by means of a set screw 94. The mounting of the rod 90 within the sleeve 92 is accomplished by a pin 96 on the end of the rod 90 which is received within a slot 98 on the sleeve 92. In this fashion, rotary movement of the rod 90, as produced by the motor 88, will produce a rotation of the rotatable spool portion 76 to produce a change in the rate of fluid which is supplied to the auger motor 44,

thereby varying the rate of material discharge.

With reference now to H6. 3, the control motor 88 is preferably a suitable conventional reversible d.c. motor controlled by a motor control circuit which automatically regulates the speed of the motor 88 in relation to the speed of the vehicle. For example, the control motor may include first and second input terminals 88A and 888 which, when supplied with a d.c. energizing voltage, effect the rotation of the control motor in opposite directions.

A d.c. signal related in amplitude to the speed of the vehicle may be generated by any suitable conventional generator such as a tachometer indicatedat 100. One side of the generator 100 may be connected to the negative or common terminal of a d.c. power supply indicated at 102 and the other side of the generator 100 may be connected through the coil 104 of a suitable conventional discriminating relay generally indicated at 106 to the arm of a potentiometer 108. The arm of the potentiometer 108 is driven in response to rotation of the control motor 88 through a mechanical drive such as the illustrated gear cluster 127 and mechanical linkage 125.

One end of the potentiometer 108 is connected to the negative or common terminal of the power supply 102 and the other end of the potentiometer 108 may be connected both to one end of a manually adjustable p0- tentiometer 110 and through a fixed resistor 112 to the negative terminal of the power supply 102; A positive d.c. voltage may be supplied from the positive output terminal of the power supply 102 through a suitable conventional on/off switch 114 to the wiper arm of the potentiometer 110. The potentiometers 108 and 110 thereby form a voltage divider and the position of the arm of the potentiometer 110 may be adjusted to adjust the energizing voltage applied across the potentiometer 108.

The discriminating relay 106 also includes a switching element 116 connected to the negative or common terminal of the power supply 102. The switching element 116 is operable in response to current flowing in one direction through the coil 104 to make electrical contact with a contact 118 and is operable in response to current flow through the coil 104 in the other direc tion to make contact with an electrical contact 120.

The contacts 118 and 120 are connected through relay coils 122 and 124 respectively to the positive output terminal of the power supply 102 via the on/off switch 114. Normally open relay contacts 126 and 128 associated with the respective coils 122 and 124 are operable to apply the positive d.c. voltage from the positive output terminal of the power supply 102 to one or the other of the control motor 88 input terminals 88A and 888 when the corresponding one of the relay coils 122 and 124 is energized.

In operation and assuming that the vehicle is initially at rest, the generator produces no output voltage and the wiper arm of the potentiometer 108 is driven by the gear train 127 to a position in which no output voltage is coupled from the wiper arm of the potentiometer to the coil 104;, i.e., at one end of its resistance element. Since no potential is applied across the relay coil 104 and no current flows therethrough, the discriminating relay contacts 118 and assume an open position and the relay contacts 126 and 128 likewise are open. The control motor 88 is thus deenergized with the vehicle at rest and the arm of the potentiometer 108 is at one end of its resistance element.

When the vehicle moves, the generator 100 produces an output voltage which initially creates a potential across the relay coil 104 causing current to flow therethrough in one direction. Current flow through the coil 104 defects the movement of the switch element 116 to energize the appropriate one of the relays 122 and 124 and thus causes the motor 88 to drive the adjustable valve 58 in a direction tending to increase the rate of material discharge.

Rotation of the motor 88 results in movement of the wiper arm of the potentiometer 108 through the gear train 127 and the mechanical linkage 125. As the wiper arm of thepotentiometer 108 is moved, the wiper arm couples an increasing portion of the voltage across the potentiometer 108 to the coil 104 until the potential coupled-from the potentiometer 108 and the voltage generated by the generator 100 are equal. When this equal voltage condition is achieved, no current flows through the coil 104 and the previously energized one of the relay coils 122 and 124 is deenergized thereby deenergizing the motor 88.

If a-constant vehicle speed is maintained, all circuit conditions remain the'same and the material feed rate remains the same. However, a change in vehicle speed either direction causes an imbalance in the potential across the coil 104 and results in a change in material feed rate. For example, if vehicle speed decreases, a signal of lesser amplitude is generated by the generator 100 and current flow is established through the coil 104 from the potentiometer to the generator 100. The appropriate relay contact 126 or 128 is closed and the motor 88 drives the wiper arm of the potentiometer 108 in a direction tending to couple a lower voltage from the potentiometer to thereby again balance the voltage acrossthe coil 104. Of course, rotation of the motor 88 in a direction tending to lower the output voltage coupled from the potentiometer 108 also lowers the rate of material discharge.

The voltage coupled from the potentiometer 108 and applied tothe coil 104 to balance the voltage from the generator 100 is related in amplitude to both the position of the arm of the potentiometer 108 and to the energizing voltage applied across the potentiometer I08. Thus, adjustment of the energizing voltage across the potentiometer 108 varies the position to which the arm of the potentiometer must be driven to balance a particular speed related voltage from the generator 100. Since manual adjustment of the potentiometer 110 varies the energizing voltage applied across the potentiometer 108, the operator may control the relationship between feed rate and vehicle speed by adjusting the potentiometer 110.

The potentiometer 110 can be set by manipulation of a control knob 123 on a control box 121 conveniently located in the cab 14 of the vehicle. The valve assembly 56 preferably is disposed at the operators station also adjacent the control box 121, with the fluid lines 62, 70, and 72 extending from the operators station to the fluid motors 34 and 44 at the rear of the vehicle (FIG. 2), and the spinner control valve 60 may be operated directly by a shaft 137 having a knob 139 on an end thereof protruding from the control box 121.

In certain instances it may be necessary to effect a discharge of material from the vehicle independently of the control motor 88. For example, in the event of an electrical failure in the control circuit, or while the truck is standing still and thus producing no signal from the generator 100, it may be desirable to re-orient the valve 58 to increase or decrease the rate of material being discharged. In accordance with the present in-' vention, the control system for the valve 58 is provided with a manual override arrangement which can change the setting of the valve 58 independently of the control motor 88.

As shown'in FIG. 4, the manual override arrangement includes a control knob 136 which is connected by an arm 138 to the gear cluster 127 defined by the gears 89 and 132 fixed on the rod 90. The arm 138 may comprise an extension of the rod 90 or may comprise a separate shaft mounted to a collar 140 on the gear 89. The rod is operable to be depressed by the control knob 136 to a first override position (FIG. 78) wherein the gear 89 is shifted out of driving engagement with the gear 87. Such shifting movement of the rod 90 is accommodated by means of the pin-and-slot connection 96 and 98 between the shaft 90 and the sleeve 92. A compression spring 142 is disposed within the sleeve 92 to bias the shaft 90 outwardly.

As may be observed in FIGS. 4 and 78, a gear 134 connected to the mechanical coupling 125 of the potentiometer 108 is of sufficient width that longitudinal shifting of the shaft 90 to the first override position will not cause disengagement of the gears 132 and 134. Therefore, the gear 134 and the potentiometer 108 will continue to be driven by the gear 132 while the valve 58 is being operated manually by the control knob 136. in this fashion, shifting of the valve 58 will produce an unbalance within the electrical control circuit via the potentiometer 108. Consequently, when the knob 136 is released, allowing the gears 87 and 89 to re-engage, the motor 88 will return the valve 58 to its original setting, i.e., it will rotate the valve stem 86 and the potentiometer 108 until the control circuit is re-balanced.

As may be viewed in FIG. 7C, the control knob 136 is operable to depress the gear cluster 127 to a second override position wherein the driving connection between the gears 134 and 132, as well as the driving connection between the gears 87 and 89, is disengaged. With the gear assembly in this second override position, the control knob 136 may be manually rotated to shift the orientation of the valve 58 independently of both the control motor88 and the potentiometer 108. This enables the valve 58 to be adjusted relative to the electrical circuit in order to effect a proper synchronization therebetween, without the valve 58 being returned to its original setting.

As concerns the valve spools 76 and 78, it will be apparent that the spool 76 may be disposed in a posture wherein the valve is closed, i.e., no fluid flows from the pump 46 to the fluid motor (FIG. 5B). As the spool 76 is rotated by the rod 90, the slots 80 and 82 will become gradually aligned to define a fluid conducting passage of progressively varying dimension. FIG. 5C depicts the situation where the valve is in a cracked state wherein only small portions of the slots are aligned and the fluid motor is receiving only a minimal flow of fluid. In FIG. 5D the valve is illustrated as being in a fullopen" position where a substantial flow of fluid is provided.

When the metering valves are disposed in a cracked position, it may be difficult for the pump 46 to supply fluid to the motors 34 and 44 in amounts sufficient to operate the motors at a sufficient rate. This problem 'is amplified by the fact that the valve 58 is in its cracked position when the vehicle is traveling at low speeds, and at such speeds the pump 46 operates at low speed. The present invention alleviates this problem through the provision of a relief in one of the spool slots 80 and 82. Such relief is preferably in the form of a recess 144 provided at the end of the slot 82. Through the provision of such a recessed portion, a greater flow of drive fluid will be supplied during initial operation of the fluid motor than would otherwise be supplied, as shown in FIG. 5C. This greater flow enables the fluid motor 44 to dispense a proper quantity of material during low speed operations of the vehicle. The spool portions of the valve 60 may also be provided with a similar arrangement if desired.

OPERATION With the vehicle being in a rest, or stopped, position and the switch 114 is in an on position, current supplied by the d.c. power source 102 will'drive the con trol motor 88 to place the valve 58 in a closed position (FIG. 5B) wherein no drive fluid is supplied to the auger motor 44. As the vehicle gradually picks up speed, a signal is produced by the generator 100. The discriminating relay coil 104 is activated, depending upon the direction of current flow therethrough, to activate an appropriate one of the booster relays 122 or 124. The energized booster relay will close its associated contact 126 or 128 to rotate the control motor in a suitable manner for progressively opening the valve 58. In this fashion, the auxiliary motor 44 will dispense material at a rate related to the speed of the vehicle. As the control motor 88 rotates, the potentiometer 108 is driven by the gear 132. When the potentiometer has been shifted by an amount sufficient to balance the signal generated by the generator 100, the discriminating relay is deactivated and the control motor 88 stops rotating. The valve 58 will thereby be maintained at a position operable to pass pressurized fluid and drive the auger 22 at a rate which is in accordance with vehicle speed.

The potentiometer may be adjusted as desired to control the voltage across the potentiometer 108 and thereby regulate, in conjunction with the generator 100, the amount of fluid which passes through the valve 58 at each given speed of the vehicle. In this manner. the amount of material discharged during each mile of vehicle travel can be selectively varied.

When there occurs a malfunction in the electric control circuit, or when it is desired to discharge material with the vehicle in a rest position, the control knob 136 may be manually depressed to a first override position (FIG. 7B). In this position the gears 87 and 89 will be disengaged, with the gears 132 and 134 remaining in driving relationship. The shaft'90, however, will be maintained in driving connection with the valve 58 via the pin and slot arrangement 96 and 98. Manual rotation of the knob 136 will thus produce a corresponding rotation of the valve 58 to regulate, independently of the control circuit, the rate of material being discharged.

While the knob 136 is in its first override position, manual rotation thereof will also impart rotation to the potentiometer 108, thus producing an imbalance in the control circuit. Consequently, when the gears 87 and 89 are brought into re-engagement following manual operation, the control motor 88 will rotate the valve 58 until the potentiometer 108 is returned to its original posture. In this fashion, the valve 58 will be automatically returned to its initial orientation following the completion of manual operation.

When it is desiredto synchronize the position of the control valve 58 with that of the electrical circuit to establish a desired operational relationship therebetween, the control knob 136 may be depressed to a second override position as shown in FIG. 7C. In this manner the gears 89 and 132 are shifted out of respective engagement with the gears 87 and 134. The valve 58v may then be adjusted independently of the control motor 88 and without disturbing the position of the potentiometer 108.

With the valve 58 positioned in a cracked orientation (FIG. 5C), such as when the vehicle is traveling at a relatively low rate of speed, the recessed part 144 of the slot 82 enables a sufficient flow of fluid to be provided to the fluid motor 44 to enable the motor to function at a satisfactory rate.

While the present invention has been described in conjunction with hydraulically-operated auxiliary motors 34 and 44, it will be appreciated that the invention could be utilized with an auxiliary driven mechanism which utilizes an internal combustion engine. In such a case the rod 90 could be mechanically linked to the adjustable throttle of the auxiliary combustion engine as shown in FIG. 6of U.S. Pat. No. 3,395,866 such that rotation of the rod 90 would produce a change in engine speed. The auxiliary engine could be utilized to drive either or both of the conveyor auger 22 and the spinner disc 30.

Still other modifications and variations of the invention will be evident to persons of ordinary skill in the art. It is intended, therefore, that the foregoing detailed descriptions of certain embodiments illustrated in the accompanying drawings be considered as exemplary only and. that the scope of the invention be ascertained from the following claims.

What is claimed is: v v

1. In a material spreading vehicle having an operators drive station; prime mover means; container means for carrying a supply of material for being spread onto a roadway; an auxiliary driven spreader mechanism carried by said vehicle remotely of said operators station for spreading said material at a selected rate; said auxiliary driven mechanism including auxiliary motor means; said auxiliary motor means including adjustable means for regulating the output of said auxiliary motor means; and control means for shiftng said adjustable means to vary the rate of material spreading; said control means comprising:

control motor means;

coupling means for drivingly connecting said control motor means to said adjustable means; means for automatically operating said control motor means in relation to the speed of said vehicle;

manually operable override means disposed at said operators station and operably connected to said coupling means for selectively disengaging said control motor means from drivingconnection with said adjustable means to afford manual shifting of said adjustable means by override independently of said control motor means; and

follow-up means operably connectable to said control motor means for controlling said control motor means in response to the orientation of saidadjustable means;

said coupling means including means for operably coupling said follow-up means and said adjustable means during automatic operation of said adjustable means by said control motor means and for maintaining such operable coupling during manual disengagement of said control motor means from said adjustable means by said override means to automatically return said adjustable means to an original pre-set posture subsequent to manual adjustment of said adjustable means by said'operator.

2. Apparatus according to claim 1 wherein said control motor means comprises a first gear; said coupling means comprising a second gear operably connected between said first gear and said adjustable means; said manually operable override means comprising a control arm operably connected to said second gear and being longitudinally shiftable to a first override position to disengage said first and second gears; said follow-up means including a third gear arranged to be drivinglyengagable with said second gear in the first override position of said manually operable means.

3. Apparatus according to claim 1 wherein said manually operable override means is operably connected to said coupling means for disengaging said follow-up means from said adjustable means such that said adjustable means is manually adjustable by said override means independently of said control motor means and said follow-up means to accommodate synchronization between said adjustable means and said control motor means.

4. Apparatus according to claim 1 wherein said adjustable means comprises a rotatable valve means; and

said coupling means including a rod connected to said valve means for relative sliding movement with respect thereto.

5. Apparatus according to claim 4 and further including a slotted sleeve connected to said valve means; said rod including a pin slidably disposed within said slot; and spring means for outwardly biasing said pin.

6. Apparatus according to claim 4 wherein said auxiliary driven mechanism comprises a rotary feed auger for dispensing material from said vehicle; said auxiliary motor comprising a hydraulic motor; a hydraulic pump being drivingly connected to said prime mover means; said valve being positioned between said hydraulic pump and said hydraulic motor to regulate the rate of fluid supplied to said hydraulic motor; said vehicle including a cab section defining an operators station; sid control arm being disposed for operation at said operators station.

7. Apparatus-according to claim 1 wherein said auxiliary motor means comprises a fluid motor, pump means being provided for supplying pressurized fluid to said fluid motor, and said adjustable means comprising valve means disposed between said pump means and said fluid motor; said valve means comprising:

a stationary valve portion having afirst elongate aperture; a shiftable valve portion having a second elongate aperture;

means drivingly connected to said control motor means for progressively moving said shiftable valve portion between a closed position wherein said apertures are disposed in non-communicating relationship and an open position wherein said apertures are in communicating relationship to define a fluid-conducting passage;

said passage being progressively enlargeable in dimension during movement of said shiftable valve portion from the closed position to the open position; and

at least one of said apertures being provided with enlargement means at an end which defines the fluid passage in an initially-opened posture of said valve means. 7 a

8. Apparatus according to claim 1 wherein said vehi cle' includes a cab section defining an operators station; said control motor means comprising a reversible electric control motor; said means for automatically operating comprising a switching circuit connected to said electric control motor for de-energizing said control motor and for energizing said control motor in a selected direction; said follow-up means including first variable resistor means having a wiper arm movable in response to movement of said coupling means; a discriminating relay; a signal generator for generating a signal related to vehicle ground speed; said discriminating relay being connected in series between said signal generator and the arm of the first variable resistor means; a second variable resistor means electrically connected to asource of fixed potential, said second operably connected between said electric controlmotor and the adjustable means for controlling the position of said adjustable means in accordance with the operation of said electric control motor; and means for operating said electric control motor to control the position of said adjustable means comprising a switching circuit connected to said electric control motor for deenergizing said control motor and for energizing said control motor in a selected direction; first variable resistor means having a wiper arm movable in-response variable resistor means having a manually movable wiper arm and being electrically connected to said first variable resistor means for serial current flow through said first variable resistor means, such that the position of the wiper arm of said second variable resistor means establishes a selectively variable potential across said first variable resistor means, and means electrically coupling said discriminating relay to said switching circuit whereby an electrical imbalance condition across the discriminating relay caused by a change in vehicle speed energizes the control motor in a direction tending to drive the arm of said first variable resistor means by an amountsufficient to balance said condition, said amount being variable in response to manual adjustment of said movable wiper arm of said second variable resistor means wherein the rate of discharge of material from said vehicleis related to the speed of the vehicle and the wiper arm positions of said first and second variable" resist-or means such that, with said vehicle being in a stopped condition, said switching circuit operates said control motor for de-energizing said auxilito movement of said adjustable means; a discriminating relay; a signal generator for generating a signal related to vehicle ground speed; said discriminating relay being connected in series between said signal generator and the arm of the first variable-resistor means; a second variable resistor means electrically connected to a source of fixed potential, said second variable resistor means having a manually movable wiper arm and being electrically connected to said first variable resistor means for serial current flow through said first variable resistor means, such that the position of the wiper arm of said second variable resistor means establishes a selectively variable potential across said first variable resistor means; and means electrically coupling said discriminating relay to said switching circuit to energize the control motor in a direction tending to drive the arm of said first variable resistor means by an amount sufficient to balance an electrical imbalance condition across the discriminating relay caused by a change in vehicle speed, saidamount being variable in response to manual adjustment or said movable ,wiper arm of said second variable resistor means, wherein the rate of discharge of material from said vehicle is related to the speed of the vehicle and the wiper arm positions of .said first and second variable resistor means such that, with said vehicle being in a stopped condition, said switching circuit operates said control motor for deenergizing said auxiliary motor means regardless of the wiper arm position of said second variable resistor means. I v

10. In a vehicle having prime mover means; an auxiliary driven mechanism carried by said vehicle for discharging material from said vehicle and including auxiliary motor means for controlling the rate of discharge of material from said vehicle; said auxiliary motor means including adjustable means for regulating the output of said auxiliary motor means;- and control means for varying the position of said adjustable means to vary the rate of discharge of said material; said control means comprising:

control -motor means; coupling means for drivingly connecting said control motor means to said adjustable means; and circuit means for automatically operating said control motor means in relation to the speed of said vehicle including:

generator means for generating a first voltage re-' first and second variable resistor means electrically connected for serial current flow through said first variable resistor means such that said second variable resistor means applies an energizing voltage to said first variable resistor means;

said first variable resistor means being operably connected to and driven by said coupling means for generating a second voltage related in amplitude tothe position of the adjustable means and the amplitude of said applied energizing voltage;

switching means electrically connected to said first and second variable resistor means for operating said control motor means in response to the relative amplitudes of said first and second voltages; and,

said second variable resistor means including manually positionable means for manually adjustably setting the amplitude of said energizing voltage so that the rate of discharge of material from said vehicle is related to the speed of the vehicle and the setting of said first and second variable resistor means such that, with said vehicle being in a stopped condition, said switching circuit operates said control motor means for de-energizing said auxiliary motor means regardless of the setting of said second variable resistor means.

11. Apparatus according to claim wherein said coupling means additionally comprises a manually operable control element for operatively disengaging said control motor means from said adjustable means while maintaining the connection between said first variable resistor means and said adjustable means so as to permit operation of said adjustable means by said manually operable control element, while preserving the said relation between the amplitude of said second voltage and the position of said adjustable means during operation of said manually operable control element.

12. In a vehicle having prime mover means; an auxiliary driven mechanism carried by said vehicle and including auxiliary motor means; said auxiliary motor means including adjustable means for regulating the output of said auxiliary motor means, and control means for shifting said adjustable means; said control means comprising:

control motor-means including first rotary means rotatable about a first rotary axis;

means'for automatically operating said control motor means in relation to the speed of said vehicle;

coupling means for drivingly connecting said control motor means to said adjustable means, said coupling means including second rotary means drivably connected to said first rotary drive means tobe rotated thereby about a second rotary axis;

follow-up means for supplying a signal to de-activate said motor means in response to pre-selected movement of said adjustable means, said follow-up means including third rotary means drivably connected to said second rotary means to be rotated thereby about a third rotary axis;

manually operable override means operatively engageable with said second rotary means to shift said second rotary means between:

a first position wherein said second rotary means is operatively coupled to said first rotary means and said third rotary means,

a second. position wherein said second rotary means is decoupled from said first rotary means and is operatively coupled to said third rotary means, such that subsequent manual adjustment of said adjustable means by said override means produces a signal from said follow-up means to return said adjustable means to an original preset posture when said second rotary means is returned to said first position, and

a third position wherein said second rotary means is de-coupled from both said first and third rotary means such that manual synchronizing adjustment of said adjustable means by said override means is accomplished independently of said control motor means and said follow-up means.

13. Apparatus according to claim 12 wherein said first and third rotary means each comprises a gear; and said second rotary means comprises a pair of co-axial gears coupled respective to saidfirst and third gears; said override means comprising a manually shiftable control arm carrying said co-axial gears.

14. Apparatus according to claim 12 wherein said auxiliary motor means comprises a fluid motor, pump means being provided for supplying pressurized fluid to said fluid motor, said adjustable means comprising valve means disposed between said pump means and said fluid motor; said valve means comprising:

a stationary valve portion having a first elongate ap erture;

a shiftable valve portion having a second elongate aperture; means drivingly connected to said control motor means for progressively moving said shiftable valve portion between a closed position wherein said apertures are disposed in non-communicating relationship and an open position wherein said apertures are in communicating relationship to define a fluid-conducting passage;

said passage being progressively enlargeable in dimension during movement of said shiftable valve portion from the closed position to the open position; and at least one of said apertures being provided with enlargement means at an end which defines the fluid passage in an initially-opened posture of said valve means.

15. Apparatus according to claim 12 wherein said vehicle includes a cab section defining an operators station; said control motor means comprising a reversible electric control motor; said means for automatically operating comprising a switching circuit connected to said electric control motor for de-energizing said control motor and for energizing said control motor in a selected direction; said follow-up means including first variable resistor means having a wiper arm movable in response to movement of said third rotary means; a discriminating-relay; a signal generator for generating a signal related to vehicle ground speed; said discriminating relay being connected in series between said signal generator and the arm of the first variable resistor means; a second variable resistor means electrically connected to a sourceof fixed potential, said second variable resistor means having a manually movable wiper arm and being electrically connected to said first variable resistor means for serial current flow through said first variable resistor means, such that the position of the wiper arm of said second variable resistor means establishes a selectively variable potential across said first variable resistor means, and means electrically means comprising:

and the wiper armipositions of said first and secondvariable resistor means such that, with said vehicle being in a stopped condition, said switching circuit operates said control motor for de-energizing said auxiliary motor means regardless of the wiper arm position of said second variable resistor means,

16. In a vehicle having prime mover means; an auxiliary driven material-spreading mechanism carried by said vehicle and including auxiliary motor means; said auxiliary'including adjustable means for regulating the output of said auxiliary: motor means; and control means for shifting said adjustable means; said control control motor means including first rotary gearmeans rotatable about a first rotary axis;

- means for automatically operating said control motor means in relation to the speed of said vehicle;

' coupling means for drivingly connecting said control motor means to said adjustable means, said coupling means including second rotary gear means drivably connected to said first rotary gear means to be rotated thereby about a second rotary axis;

- follow-up means for supplying a-signal to de-activate said motor means in response to pre-selected movement of said adjustable means, said follow-up means including third rotary gear means drivably connected to said second rotarygear means to be I rotated thereby about a third rotary axis; manually operable override meansoperatively engageable with said second rotary gear means to longitudinally shift said second rotary gear means between: e a first position wherein said second rotary gear means is operatively coupled tosaid first rotary gear means and said third rotary gear means, and a second position wherein said second rotary gear means is de-coupled from said first rotary gear means and operatively coupled to said third r0- tary gear means; said override means being drivably connected to said second rotary gear means with the latter in said second position, and being manually rotat able about said second rotary axis to manually adjust said adjustable means and said third rotary means such that manual adjustment of said adjustment means produces a signal from said follow-up means for returning said adjustable means to an original preset posture when said second rotary gear means is returned to said position.

l7.- Apparatus according to claim 16 wherein said manually operable override means is operativelyfengageable with said second rotary gear means-to further longitudinally shift said second rotary gear means to a third position wherein said second rotary gear means is I de-coupled from both said first and third rotary gear means such that manual synchronizing adjustment of said adjustable means is accomplished independently of said control motor means and said follow-up means. 

1. In a material spreading vehicle having an operator''s drive station; prime mover means; container means for carrying a supply of material for being spread onto a roadway; an auxiliary driven spreader mechanism carried by said vehicle remotely of said operator''s station for spreading said material at a selected rate; said auxiliary driven mechanism including auxiliary motor means; said auxiliary motor means including adjustable means for regulating the output of said auxiliary motor means; and control means for shiftng said adjustable means to vary the rate of material spreading; said control means comprising: control motor means; coupling means for drivingly connecting said control motor means to said adjustable means; means for automatically operating said control motor means in relation to the speed of said vehicle; manually operable override means disposed at said operator''s station and operably connected to said coupling means for selectively disengaging said control motor means from driving connection with said adjustable means to afford manual shifting of said adjustable means by override independently of said control motor means; and follow-up means operably connectable to said control motor means for controlling said control motor means in response to the orientation of said adjustable means; said coupling means including means for operably coupling said follow-up means and said adjustable means during automatic operation of said adjustable means by said control motor means and for maintaining such operable coupling during manual disengagement of said control motor means from said adjustable means by said override means to automatically return said adjustable means to an original pre-set posture subsequent to manual adjustment of said adjustable means by said operator.
 2. Apparatus according to claim 1 wherein said control motor means comprises a first gear; said coupling means comprising a second gear operably connected between said first gear and said adjustable means; said manually operable override means comprising a control arm operably connected to said second gear and being longitudinally shiftable to a first override position to disengage said first and second gears; said follow-up means including a third gear arranged to be drivingly engagable with said second gear in the first override position of said manually operable means.
 3. Apparatus according to claim 1 wherein said manually operable override means is operably connected to said coupling means for disengaging said follow-up means from said adjustable means such that said adjustable means is manually adjustable by said override means independently of said control motor means and said follow-up means to accommodate synchronization between said adjustable means and said control motor means.
 4. Apparatus according to claim 1 wherein said adjustable means comprises a rotatable valve means; and said coupling means including a rod connected to said valve means for relative sliding movement with respect thereto.
 5. Apparatus according to claim 4 and further including a slotted sleeve connected to said valve means; said rod including a pin slidably disposed within said slot; and spring means for outwardly biasing said pin.
 6. Apparatus according to claim 4 wherein said auxiliary driven mechanism comprises a rotary feed auger for dispensing material from said vehicle; said auxiliary motor comprising a hydraulic motor; a hydraulic pump being drivingly connected to said prime mover means; said valve being positioned between said hydraulic pump and said hydraulic motor to regulate the rate of fluid supplied to said hydraulic motor; said vehicle including a cab sectiOn defining an operator''s station; sid control arm being disposed for operation at said operator''s station.
 7. Apparatus according to claim 1 wherein said auxiliary motor means comprises a fluid motor, pump means being provided for supplying pressurized fluid to said fluid motor, and said adjustable means comprising valve means disposed between said pump means and said fluid motor; said valve means comprising: a stationary valve portion having a first elongate aperture; a shiftable valve portion having a second elongate aperture; means drivingly connected to said control motor means for progressively moving said shiftable valve portion between a closed position wherein said apertures are disposed in non-communicating relationship and an open position wherein said apertures are in communicating relationship to define a fluid-conducting passage; said passage being progressively enlargeable in dimension during movement of said shiftable valve portion from the closed position to the open position; and at least one of said apertures being provided with enlargement means at an end which defines the fluid passage in an initially-opened posture of said valve means.
 8. Apparatus according to claim 1 wherein said vehicle includes a cab section defining an operator''s station; said control motor means comprising a reversible electric control motor; said means for automatically operating comprising a switching circuit connected to said electric control motor for de-energizing said control motor and for energizing said control motor in a selected direction; said follow-up means including first variable resistor means having a wiper arm movable in response to movement of said coupling means; a discriminating relay; a signal generator for generating a signal related to vehicle ground speed; said discriminating relay being connected in series between said signal generator and the arm of the first variable resistor means; a second variable resistor means electrically connected to a source of fixed potential, said second variable resistor means having a manually movable wiper arm and being electrically connected to said first variable resistor means for serial current flow through said first variable resistor means, such that the position of the wiper arm of said second variable resistor means establishes a selectively variable potential across said first variable resistor means, and means electrically coupling said discriminating relay to said switching circuit whereby an electrical imbalance condition across the discriminating relay caused by a change in vehicle speed energizes the control motor in a direction tending to drive the arm of said first variable resistor means by an amount sufficient to balance said condition, said amount being variable in response to manual adjustment of said movable wiper arm of said second variable resistor means wherein the rate of discharge of material from said vehicle is related to the speed of the vehicle and the wiper arm positions of said first and second variable resistor means such that, with said vehicle being in a stopped condition, said switching circuit operates said control motor for de-energizing said auxiliary motor means regardless of the wiper arm position of said second variable resistor means.
 9. In a vehicle having an operator''s station; prime mover means for propelling said vehicle; an auxiliary driven mechanism for discharging material from said vehicle including auxiliary motor means on said vehicle remote from said operator''s station; adjustable means for controlling the speed of said auxiliary motor means; a reversible electric control motor; mechanical means operably connected between said electric control motor and the adjustable means for controlling the position of said adjustable means in accordance with the operation of said electric control motor; and means for operating said electric control motor to control the position of said adjustable means comprising a switching circuit Connected to said electric control motor for de-energizing said control motor and for energizing said control motor in a selected direction; first variable resistor means having a wiper arm movable in response to movement of said adjustable means; a discriminating relay; a signal generator for generating a signal related to vehicle ground speed; said discriminating relay being connected in series between said signal generator and the arm of the first variable resistor means; a second variable resistor means electrically connected to a source of fixed potential, said second variable resistor means having a manually movable wiper arm and being electrically connected to said first variable resistor means for serial current flow through said first variable resistor means, such that the position of the wiper arm of said second variable resistor means establishes a selectively variable potential across said first variable resistor means; and means electrically coupling said discriminating relay to said switching circuit to energize the control motor in a direction tending to drive the arm of said first variable resistor means by an amount sufficient to balance an electrical imbalance condition across the discriminating relay caused by a change in vehicle speed, said amount being variable in response to manual adjustment of said movable wiper arm of said second variable resistor means, wherein the rate of discharge of material from said vehicle is related to the speed of the vehicle and the wiper arm positions of said first and second variable resistor means such that, with said vehicle being in a stopped condition, said switching circuit operates said control motor for de-energizing said auxiliary motor means regardless of the wiper arm position of said second variable resistor means.
 10. In a vehicle having prime mover means; an auxiliary driven mechanism carried by said vehicle for discharging material from said vehicle and including auxiliary motor means for controlling the rate of discharge of material from said vehicle; said auxiliary motor means including adjustable means for regulating the output of said auxiliary motor means; and control means for varying the position of said adjustable means to vary the rate of discharge of said material; said control means comprising: control motor means; coupling means for drivingly connecting said control motor means to said adjustable means; and circuit means for automatically operating said control motor means in relation to the speed of said vehicle including: generator means for generating a first voltage related in amplitude to the speed of the vehicle; first and second variable resistor means electrically connected for serial current flow through said first variable resistor means such that said second variable resistor means applies an energizing voltage to said first variable resistor means; said first variable resistor means being operably connected to and driven by said coupling means for generating a second voltage related in amplitude to the position of the adjustable means and the amplitude of said applied energizing voltage; switching means electrically connected to said first and second variable resistor means for operating said control motor means in response to the relative amplitudes of said first and second voltages; and, said second variable resistor means including manually positionable means for manually adjustably setting the amplitude of said energizing voltage so that the rate of discharge of material from said vehicle is related to the speed of the vehicle and the setting of said first and second variable resistor means such that, with said vehicle being in a stopped condition, said switching circuit operates said control motor means for de-energizing said auxiliary motor means regardless of the setting of said second variable resistor means.
 11. Apparatus according to claim 10 wherein said coupling means additionally comprises a manually operable control elemEnt for operatively disengaging said control motor means from said adjustable means while maintaining the connection between said first variable resistor means and said adjustable means so as to permit operation of said adjustable means by said manually operable control element, while preserving the said relation between the amplitude of said second voltage and the position of said adjustable means during operation of said manually operable control element.
 12. In a vehicle having prime mover means; an auxiliary driven mechanism carried by said vehicle and including auxiliary motor means; said auxiliary motor means including adjustable means for regulating the output of said auxiliary motor means, and control means for shifting said adjustable means; said control means comprising: control motor means including first rotary means rotatable about a first rotary axis; means for automatically operating said control motor means in relation to the speed of said vehicle; coupling means for drivingly connecting said control motor means to said adjustable means, said coupling means including second rotary means drivably connected to said first rotary drive means to be rotated thereby about a second rotary axis; follow-up means for supplying a signal to de-activate said motor means in response to pre-selected movement of said adjustable means, said follow-up means including third rotary means drivably connected to said second rotary means to be rotated thereby about a third rotary axis; manually operable override means operatively engageable with said second rotary means to shift said second rotary means between: a first position wherein said second rotary means is operatively coupled to said first rotary means and said third rotary means, a second position wherein said second rotary means is decoupled from said first rotary means and is operatively coupled to said third rotary means, such that subsequent manual adjustment of said adjustable means by said override means produces a signal from said follow-up means to return said adjustable means to an original pre-set posture when said second rotary means is returned to said first position, and a third position wherein said second rotary means is de-coupled from both said first and third rotary means such that manual synchronizing adjustment of said adjustable means by said override means is accomplished independently of said control motor means and said follow-up means.
 13. Apparatus according to claim 12 wherein said first and third rotary means each comprises a gear; and said second rotary means comprises a pair of co-axial gears coupled respective to said first and third gears; said override means comprising a manually shiftable control arm carrying said co-axial gears.
 14. Apparatus according to claim 12 wherein said auxiliary motor means comprises a fluid motor, pump means being provided for supplying pressurized fluid to said fluid motor, said adjustable means comprising valve means disposed between said pump means and said fluid motor; said valve means comprising: a stationary valve portion having a first elongate aperture; a shiftable valve portion having a second elongate aperture; means drivingly connected to said control motor means for progressively moving said shiftable valve portion between a closed position wherein said apertures are disposed in non-communicating relationship and an open position wherein said apertures are in communicating relationship to define a fluid-conducting passage; said passage being progressively enlargeable in dimension during movement of said shiftable valve portion from the closed position to the open position; and at least one of said apertures being provided with enlargement means at an end which defines the fluid passage in an initially-opened posture of said valve means.
 15. Apparatus according to claim 12 wherein said vehicle includes a cab section defining an operator''s station; said control motor means compRising a reversible electric control motor; said means for automatically operating comprising a switching circuit connected to said electric control motor for de-energizing said control motor and for energizing said control motor in a selected direction; said follow-up means including first variable resistor means having a wiper arm movable in response to movement of said third rotary means; a discriminating relay; a signal generator for generating a signal related to vehicle ground speed; said discriminating relay being connected in series between said signal generator and the arm of the first variable resistor means; a second variable resistor means electrically connected to a source of fixed potential, said second variable resistor means having a manually movable wiper arm and being electrically connected to said first variable resistor means for serial current flow through said first variable resistor means, such that the position of the wiper arm of said second variable resistor means establishes a selectively variable potential across said first variable resistor means, and means electrically coupling said discriminating relay to said switching circuit whereby an electrical imbalance condition across the discriminating relay caused by a change in vehicle speed energizes the control motor in a direction tending to drive the arm of said first variable resistor means by an amount sufficient to balance said condition, said amount being variable in response to manual adjustment of said movable wiper arm of said second variable resistor means wherein the rate of discharge of material from said vehicle is related to the speed of the vehicle and the wiper arm positions of said first and second variable resistor means such that, with said vehicle being in a stopped condition, said switching circuit operates said control motor for de-energizing said auxiliary motor means regardless of the wiper arm position of said second variable resistor means.
 16. In a vehicle having prime mover means; an auxiliary driven material-spreading mechanism carried by said vehicle and including auxiliary motor means; said auxiliary including adjustable means for regulating the output of said auxiliary motor means; and control means for shifting said adjustable means; said control means comprising: control motor means including first rotary gear means rotatable about a first rotary axis; means for automatically operating said control motor means in relation to the speed of said vehicle; coupling means for drivingly connecting said control motor means to said adjustable means, said coupling means including second rotary gear means drivably connected to said first rotary gear means to be rotated thereby about a second rotary axis; follow-up means for supplying a signal to de-activate said motor means in response to pre-selected movement of said adjustable means, said follow-up means including third rotary gear means drivably connected to said second rotary gear means to be rotated thereby about a third rotary axis; manually operable override means operatively engageable with said second rotary gear means to longitudinally shift said second rotary gear means between: a first position wherein said second rotary gear means is operatively coupled to said first rotary gear means and said third rotary gear means, and a second position wherein said second rotary gear means is de-coupled from said first rotary gear means and operatively coupled to said third rotary gear means; said override means being drivably connected to said second rotary gear means with the latter in said second position, and being manually rotatable about said second rotary axis to manually adjust said adjustable means and said third rotary means such that manual adjustment of said adjustment means produces a signal from said follow-up means for returning said adjustable means to an original preset posture when said second rotary gear means is returned to said position.
 17. Apparatus accordinG to claim 16 wherein said manually operable override means is operatively engageable with said second rotary gear means to further longitudinally shift said second rotary gear means to a third position wherein said second rotary gear means is de-coupled from both said first and third rotary gear means such that manual synchronizing adjustment of said adjustable means is accomplished independently of said control motor means and said follow-up means. 